Just 2 percent of people can find the number 20 in this sea of 2s in less than 6 seconds

Can you prove to your friends you are ?

On the face of it, this looks like a simple one as hidden within the dozens of 02s, there is a 20 waiting to be found. Sounds easy enough but when it has proven elusive for the vast majority of those who have already had a go. As a result, anyone who can find the 20 in less than six seconds is faster than 98% of people. It has just a 2% completion pass rate in the time frame, meaning if you can do it faster you certainly get the bragging rights. The image of the rows of numbers was shared by .

If you can’t spot it, look away now as we reveal the answer…Try looking nine rows up from the bottom, around the middle. Be warned, we're about to give you the answer, so if you're still trying to work it out, please look away now.

Keeping your active is known to help improve cognitive performance, enhance memory, and help with focus and attention. Some even believe that regular brain workouts can delay the symptoms of dementia. Many use and puzzles as a way to keep their minds active and it’s thought that adding the dimension of speed to these can add to the benefits even more. In return, by doing them regularly, you'll find that your mind is sharper and that your memory and cognitive abilities improve.

'Fiendish' puzzles like this aren't just good for keeping the kids quiet for a couple of minutes, they're also a great form of mental exercise. In fact, research suggests brainteasers may improve your cognitive skills, better your mental speed, improve your attention span, and even go some in reducing your risk of dementia.

Aaron Seitz, PhD., professor of psychology and director of the Brain Game Centre at the University of California in Riverside told Real Simple: "Studies show that staying mentally fit is important for long-term cognitive health, but the difficulty is figuring out exactly how to do it.”

He added that some games work differently for people and finding your own challenge might be the best thing to do. "If you think about diet and exercise routines, some things work better for some people than others, and the same is true with brain games,” he said. It is not clear if brain games and teasers really improve your cognitive abilities, but they can help to keep you relaxed and fresh, leading to indirect benefits.

Plus, brain teasers are fun – what better way to best your friends than to set the timer and see who can solve it first? Have a go at other optical illusions .

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